# Better Logging

## Tags

* type: enhancement
* keywords: deployment, 404
* assigned: bonfacem, pjotrp
* priority: low

## Introduction

=> https://flask.palletsprojects.com/en/2.0.x/errorhandling/

Some of those 404's in our log mean that we forgot to package something; for example:

=> https://git.genenetwork.org/guix-bioinformatics/guix-bioinformatics/commit/e80fe4ddcf15e21004b8135cf8af34b458697f64

Removing the 404's would prevent us from catching important errors if ever they occur. I suggest we fix the 404's; some of them have a cascading effect, like the font-awesome missing "webfonts" folder I just fixed that leads to a lot of unnecessary 404s.

For error handling, I think that will evolve with the code-base with time as it gets leaner. One way the aforementioned flask page recommends handling errors is by creating custom errors for your particular subject-domain needs and probably send a 5xx message that's more helpful. At the moment we are using one error-handler for everything(notice the generic "Exception")! See:

```
@app.errorhandler(Exception)
def handle_bad_request(e):
    err_msg = str(e)
    logger.error(err_msg)
    logger.error(request.url)
    # get the stack trace and send it to the logger
    exc_type, exc_value, exc_traceback = sys.exc_info()
    logger.error(traceback.format_exc())
    now = datetime.datetime.utcnow()
    time_str = now.strftime('%l:%M%p UTC %b %d, %Y')
    formatted_lines = [request.url
                       + " (" + time_str + ")"] + traceback.format_exc().splitlines()

    # Handle random animations
    # Use a cookie to have one animation on refresh
    animation = request.cookies.get(err_msg[:32])
    if not animation:
        list = [fn for fn in os.listdir(
            "./wqflask/static/gif/error") if fn.endswith(".gif")]
        animation = random.choice(list)

    resp = make_response(render_template("error.html", message=err_msg,
                                         stack=formatted_lines, error_image=animation, version=GN_VERSION))

    # logger.error("Set cookie %s with %s" % (err_msg, animation))
    resp.set_cookie(err_msg[:32], animation)
    return resp
```

I'll look a way for removing this:

```
    exc_type, exc_value, exc_traceback = sys.exc_info()
    logger.error(traceback.format_exc())
```

with a more sane, but probably still useful, log. That's where I problem IIUC lies.

### Resolution

The problem of improving better logging has been documented in:

=> /topics/better-logging

Most recently, all noisy logging was removed in:

=> https://github.com/genenetwork/genenetwork2/pull/730/commits/313b041a1c382042b6028054c6c17218eed1c9c5 Delete logger import (commit)

=> https://github.com/genenetwork/genenetwork2/pull/730/commits/afe2bd8ce689994da6f2f0cca420b472ee3b7fff Delete utility.logger (commit)

=> https://github.com/genenetwork/genenetwork2/commit/9d0f492d8a999c1a3eb6525b0ae72bbbcaad4279 Remove usage of "logger" and un-necessary comments wrt the same

We are aware that at the moment we are using one error-handler for everything, and this, together with any other logging issues should be tackled in another separate issue.

* closed